Thin film magnet head with improved performance

ABSTRACT

After forming the first shield layer 23 on a basic substrate 21 and 22, a GMR film 25 is formed and embedded in the shield gap layers 24 and 26, in addition, a first insulation layer 28&#39; where the edge defines a reference position of a throat height zero is formed on a first magnetic layer 27, a gap layer 28 is formed on a magnetic pole portion of the first magnetic layer 27 and the first insulation layer, then a second magnetic layer 29 extended above the first insulation layer 38&#39; from the upper side of the magnetic pole portion of the first magnetic layer 27 is formed, after smoothing its surface by the second insulation layer 31, thin film coils 32 and 34 are formed on this second insulation layer, and the third magnetic layer 36 is formed on the insulation layers 33 and 35 where the magnetic pole portion and the thin film coil of the second above magnetic layer are isolated. In order to cancel the saturation of the magnetic flux in a magnetic pole portion effectively , and to prevent the widening of width the effective track and a decrease in the yield, the third above magnetic layer is made retreated from the air bearing surface, and is connected to rear a region from the magnetic pole portion of the second magnetic layer. A rear region of the magnetic pole portion of the second magnetic layer 29 is made in the shape of fan and connected to the third magnetic layer 36 over enough area so that the magnetic flux might not be saturated even when the tip portion of the upper pole is retreated from the air bearing surface.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a thin film magnetic head and a methodof manufacturing the same, and more particularly to a composite typethin film magnetic head constructed by stacking an inducting typewriting magnetic transducing element and a magnetoresistive type readingmagnetic transducing element, particularly a technique for improving aperformance of a thin film writing magnetic head.

2. Description of the Related Art

Recently a surface recording density of a hard disc device has beenimproved, and it has been required to develop a thin film magnetic headhaving an improved performance accordingly.

The composite type thin film magnetic head has a structure for stackinga recording head intended for the writing and a reproducing headintended for the reading out, and a magnetoresistive element has beenwidely used in order to improve the performance of the reproducing head.

In general, as such a magnetoresistive element, the element utilizinganisotropic magnetoresistive (AMR) effect has been used so far, butthere has been further developed a GMR reproducing element utilizing agiant magnetoresistive (GMR) effect having a resistance change ratiohigher than the normal anisotropic magnetoresistive effect by severaltimes. In the present specification, elements exhibiting amagnetoresistive effect such as these AMR and GMR reproducing elementsare termed as a magnetoresistive reproducing element or MR reproducingelement.

By using the AMR reproducing element, a very high surface recordingdensity of several gigabits per a unit square inch has been realized,and a surface recording density can be further increased by using theGMR element. By increasing a surface recording density in this manner,it is possible to realize a hard disc device which has a very largestorage capacity of more than 10 gigabytes and is still small in size. Aheight (MR Height: MRH) of a magnetoresistive reproducing element is oneof factors which determine a performance of a reproducing head includinga magnetoresistive reproducing element. The MR height MRH is a distancemeasured from an air bearing surface on which one end face of themagnetoresistive reproducing element is exposed to the other edge of theelement remote from the air bearing surface. During a manufacturingprocess of the magnetic head, a desired MR height MRH can be obtained bycontrolling an amount of polishing the air bearing surface.

At the same time, a performance of a recording head is also required tobe improved, in accordance with improvement of performance of thereproducing head. In order to increase a surface recording density, itis necessary to make a track density on a magnetic record medium as highas possible. For this purpose, a width of a write gap at the air bearingsurface has to be reduced to a value within a range from several micronmeters to several sub-micron meters. In order to satisfy such arequirement, the semiconductor manufacturing process has been adoptedfor manufacturing the thin film magnetic head.

One of factors determining a performance of an inductive type thin filmwriting magnetic head is a throat height TH. This throat height TH is adistance of a pole portion measured from the air bearing surface to anedge of an insulating layer which serves to separate a thin film coilfrom the air bearing surface. It has been required to shorten thisdistance as small as possible. The reduction of this throat height isalso decided by the amount of grinding from the air bearing surface.Therefore, in order to improve the performance of the thin film magneticrecording head, it is important that the recording head and thereproducing head are formed with best balance.

FIGS. 1a, 1b-9a, and 9b are cross-sectional views vertical to the airbearing surface showing the successive manufacturing steps of aconventional standard thin film magnetic head, and a cross-sectionalview in which the magnetic pole section is cut in parallel to the airbearing surface. Moreover, FIGS. 10-12 are a cross-sectional view of theentire conventional completed thin film magnetic head, a cross-sectionalview of the magnetic pole section, and a plan view of the entire thinfilm magnetic head, respectively. Moreover, the thin film magnetic headof this embodiment is a composite type thin film magnetic head formed bystacking the induction type thin film writing magnetic head and the MRreproduction reading element.

First of all, as shown in FIGS. 1a and 1b, an Insulation layer 2consisting of for example alumina (Al₂ O₃) is deposited on a basicsubstrate 1 consisting of non-magnetic and electrical insulationmaterial for example, such as AlTiC with a thickness of about 5-10 μm.

Next, as shown in FIGS. 2a and 2b, a lower shield layer 3, whichcomposes a magnetic shield protecting the MR reproduction element of thereproducing head from the influence of the external magnetic field, isformed with the thickness of 3 μm.

Afterwards, as shown in FIGS. 3a and 3b, after spattering and depositingalumina as a shield gap layer 4 of a thickness of 100-150 nm, a magneticresistance layer 5 consisting of a material with the effect of magneticresistance and composing the MR reproduction element is formed on theshield gap layer with a thickness of tens nano meter, thereby makinghigh precise mask alignment.

Then, as shown in the FIG. 4, again, a shield gap layer 6 is formed sothat the magnetic resistance layer 5 is embedded in the shield gaplayers 4 and 6.

Next, as shown in the FIG. 5, a magnetic layer 7 consisting of permalloyis formed with the film thickness of 3 μm. This magnetic layer 7 has notonly a function of the upper shield layer which magnetically shields theMR reproduction element together with the above described lower shieldlayer 3, but also has a function of a lower magnetic layer of the thinfilm magnetic writing head. Herein, for convenience' sake of theexplanation, this magnetic layer 7 is called as a first magnetic layerby paying attention to it a magnetic layer composing a writing magnetichead.

Then, on the first magnetic layer 7, after a light gap layer 8consisting of non-magnetic material, for example alumina is formed withfilm thickness of about 200 nm, a second magnetic layer 9 consisting ofmaterial with high saturation magnetic flux density such as, forexample, permalloy (Ni:50 wt %, Fe:50 wt %) and nitride iron (FeN) isformed with a desired shape by high precise mask alignment. Secondmagnetic layer 9 molded in a given shape is called a pole chip, and thewidth of the track is defined as a width W.

In this case, when a dummy pattern 9' for connecting a lower pole (firstmagnetic layer) and an upper pole (third magnetic layer), which isformed latter, are formed simultaneously, it is possible to make anopening for through-hole after a polishing or chemistry-mechanicalpolishing (CMP).

In order to prevent a width of effective writing track from beingwidened, that is, in order to prevent a magnetic flux from being widenedin the lower pole at the data writing, also a gap layer 8 insurroundings of the pole chip 9 and the lower pole 7 (first magneticlayer) are etched by an ion beam etching, such as, ion miring. Eventhough its state is shown in FIG. 5b, this structure is called as atrim, and this portion becomes a magnetic pole section in the firstmagnetic layer.

Next, as shown in FIGS. 6a and 6b, after an insulating layer, forexample, alumina film 10 is formed with the thickness of about 3 μm, thewhole is, for example, made smooth by CMP.

Subsequently, after forming a photoresist layer 11 of electricalinsulation to a given pattern by the mask alignment of high precision, athin film coil 12 as the first layer consisting, for example, of copperis formed on the photoresist layer 11.

Continuously, as shown in FIGS. 7a and 7b, after forming an insulatingphotoresist layer 13 is formed on the thin film coil 12 by the maskalignment of high accuracy again, in order to make the surface smooth,the calcining (baking) processing is given with the temperature of forexample 250-300° C.

In addition, as shown in FIGS. 8a and 8b, the thin film coils 14 as thesecond layer are formed on the smoothed surface of this photoresistlayer 13. Next, after forming a photoresist layer 15 with highlyaccurate mask alignment on the thin film coils 14 as this second layer,in order to make the surface smooth again, the calcining (baking)processing is given with the temperature of for example 250° C.

As described above, the reason why photoresist layers 11, 13 and 15 areformed with mask alignment of high accuracy, is that throat height andMR height are defined by a reference position at the end edge of themagnetic pole section side of the photoresist layer.

Next, as shown in FIGS. 9a and 9b, a third magnetic layer 16 consistingof for example permalloy is selectively formed on the second magneticlayer 9 (pole chip) and the photoresist layers 11, 13 and 15 with thethickness of 3 μm according to desired pattern.

This third magnetic layer 16 comes in contact with the first magneticlayer 7 at a rear position away from the magnetic pole section through adummy pattern 9', thin film coil 12, 14 is extended through a closedmagnetic circuit composed by the 1st, 2nd and 3rd magnetic layers.

In addition, an overcoat layer 17 consisting of alumina deposited fromthe exposed surface of the third magnetic layer 16.

Finally, the side surface forming the magnetic resistance layer 5 andthe gap layer 8 is ground, thereby forming an air bearing surface (ABS)18 opposite to the magnetic record medium. Magnetic resistance layer 5is also ground in the formation process of this air bearing surface 18,and thus, MR reproduction element 19 is obtained. In this way, the abovedescribed throat height TH and the MR height MRH are decided. Itsappearance is shown in FIG. 10. In an actual thin film magnetic head,the conductor and the point of contact pad for performing electricalconnection for the thin film coils 12, 14 and a MR reproduction element19 are formed, but this is not shown.

As shown in FIG. 10, an angle θ between line segments S connectingcorners of side surfaces of photoresist layers 11, 13, 15 for isolatingthe thin film coils 12, 14 and an upper surface of the third magneticlayers 16 is called as an apex angle thereby becoming an importantfactor for deciding a performance of the thin film magnetic headtogether with the above described throat height TH and MR height.

Moreover, as shown in FIG. 12 by the plane, a width W of the magneticpole section 20 between the second magnetic layer 9 and the 3rd magneticlayer 16 is made narrow, and the width of the track recorded in themagnetic record medium is defined by this width, so that it is necessaryto narrow this width W as much as possible to achieve a high surfacerecording density. Moreover, in this FIG. 12, for the shake's ofconvenience of drawing, the thin film coils 12, 14 are made concentriccircle.

Well, in forming conventional thin film magnetic head, especially, theproblem is that after forming the coil, the coil section covered withthe photoresist insulation layer and risen in the mountain shape,especially, it is a difficulty of a fine formation of the upper pole(yoke pole) formed along the inclined part (Apex). That is, thehitherto, in case of forming the upper pole, after plating the materialfor the upper pole such as permalloy on the mountain shaped coil withthe height of about 7-10 μm, the photoresist is spread with thethickness of 3-4 μm, after which a given pattern is formed by using thephotolithography technology. Herein, If 3 μm or more is necessary as thefilm thickness of resist that the patterning is performed by theregister strike on the mountain shaped coil, the photoresist of theabout 8-10 μm thickness will be spread under the inclined portion.

One the one hand, in the upper pole formed on the write gap layer whichis formed on the surface and the smooth surface of a certain mountainshaped coil section having the height difference of about such 10 μm, itis necessary to form the narrow track of the recording head near theedge in the photoresist insulation layer (11, 13 of for example FIG. 7).Therefore, it is necessary to form the pattern of the width of 1 μm withthe photoresist film of thickness of 8-10 μm.

However, even if the narrow width pattern of 1 μm level is formed with aphotoresist film as thick as 8-10 μm, in case of exposing thephotolithography, the pattern crumble or the like due to the reflectionof light is generated, and the decrease in the resolution is forced dueto the thick resist, so that it is extremely difficult to form a toppole for forming the narrow track by the patterning with accuracy.

Then, as is shown in the above conventional embodiment, assuming thatdata is written with the pole chip capable of forming the narrow trackwidth of the recording head, after forming this pole chip, by adopting amethod of connecting the upper pole to this pole chip, in other words,by adopting a structure divided into two, that is, a pole chip fordetermining the track width and an upper pole for inducing magneticflux, the above problem has been advantageously improved.

However, in the thin film magnetic head formed as in the above,particularly, in the recording head, the problem described as followswas left now as in the past.

(1) The contact area of a pole chip and an upper pole is small,moreover, the contact portion touches it vertically, so that it is easyto saturate magnetic flux with the part, therefore, the writingcharacteristic of satisfying enough is not obtained.

(2) Throat height TH and MR height MRH are decided based on the edge onthe pole portion side of the insulating layer which insulating separatesthe thin film coil, but the insulating layer is weak to heat since it isusually formed with a photoresist organic insulating layer.

Therefore, it melts by heat-treating about 250° C. added when the thinfilm coil is formed or softens, and the pattern size of the insulatinglayer changes, and the size of throat height TH and MR height MRH mightshift from the design value of the desire.

(3) The positional relation of a pole chip and an upper pole is decidedby alignment at photolithography, so that as seen from the air bearingsurface, this positional relation is shifted to one side greatly, but inthis case, data writing is performed even in the upper pole and thus theeffective track width is widened. Therefore, the malfunction of writingthe data in the place other than in the hard disk board to be recordedoriginally, is generated.

SUMMARY OF THE INVENTION

An object of the present invention is to achieve the above problems witheffectively and to provide a thin film magnetic head in which thecontact area of a pole chip and an upper pole is effectively expanded,and the saturation of the magnetic flux at the magnetic pole sectionworried at the hitherto is completely canceled, and its effectivemanufacturing method.

Also, another object of the present invention is to a thin film magnetichead in which the pattern of the insulation layer as a standard at theposition to the air bearing surface does not melt by heat-treating about250° C. added at the time of forming the thin film coil, and thus, thethroat height TH and MR height can be obtained as the desired designvalue with stability, and its effective manufacturing method.

Moreover, other object of the present invention is to provide a thinfilm magnetic head in which widening of the width of the effective trackand the decrease in the yield or the like were also canceled, and itsmanufacturing method.

According to the present invention, there is provided a thin filmmagnetic head comprising: a first magnetic layer having a pole portionopposite to a magnetic record medium, a second magnetic layer oppositeto the magnetic record medium and having a pole portion with a widthdefining a width of a record track, for constructing an air bearingsurface together with an end face of the pole portion and an end face ofthe pole portion of the first magnetic layer, a third magnetic layercontacted to the second magnetic layer at the side opposite to the firstmagnetic layer and magnetically coupled to the first magnetic layer at arear position separated from the air bearing surface, a gap layerconsisting of non-magnetic material inserted between the pole portion ofthe first magnetic layer and the pole portion of the second magneticlayer, a thin film coil having a portion supported between the firstmagnetic layer and the second and third magnetic layers in the stateisolated by an insulating layer, and a base substrate for supporting thefirst, second and third magnetic layers, the gap layer, the insulatinglayer and the thin film coil, characterized in that the second magneticlayer is extended to the region after than the pole portion of the firstmagnetic layer along a part of the face at the side opposite to thefirst magnetic layer, of the insulating layer supported in the stateisolating the thin film coil, thereby touching the second magnetic layerto the third magnetic layer at the extended region.

In a suitable embodiment of the thin film magnetic head according to thepresent invention, the width of second magnetic layer is widened at theregion rear the pole portion.

In this case, the widened angle of the second magnetic layer at theregion rear than the pole portion is 40˜180°.

In addition, in the present invention, the second magnetic layerconsists of substance having a high saturation flux density.

Also, the tip portion of the second magnetic layer is made backed upfrom the air bearing surface, so as not expose the touched portion ofthe third magnetic layer and the second magnetic layer on the airbearing surface. The distance backed up from the air bearing surface ismade substantially 2-5 μm.

In addition, in the embodiment of the thin film magnetic head accordingto the present invention, the insulation layer where the end edge of themagnetic pole section side becomes a reference position to the airbearing surface is provided on the above first magnetic layer, thesurface of this insulation layer is covered with the gap layerconsisting of the above non-magnetic material, and the above secondmagnetic layer is arranged along the surface opposite to the aboveinsulation layer of this gap layer the above second magnetic layer.

Moreover, in the present invention, a magnetoresistive readingreproducing element insulated in electrically and shielded inmagnetically is arranged so as to expose its end face on the above airbearing surface between the above basic substance and the first magneticlayer to construct a composite thin film magnetic head.

In addition, the manufacturing method of the thin film magnetic headaccording to the present invention comprising: step of forming a firstmagnetic layer having a magnetic pole section so as to support it by abasic substrate, a step of forming a first insulating layer having anend edge of the magnetic pole section side as a reference position forthe air bearing surface, a step of forming a gap layer consisting ofnon-magnetic material on the magnetic pole portion in the above firstmagnetic layer and the above first insulation layer, a step of forming asecond magnetic layer over the magnetic pole portion in the above firstmagnetic layer and the rear region therefrom on the gap layer, a step offorming a thin film coil supported in the state isolated with each otherby the second insulation layer above the first insulating layer, a stepof forming on the above second insulation layer a third magnetic layercoming in contact with the above second magnetic layer at the regionrear rather than at least the magnetic pole portion, and coming incontact with the above first magnetic layer at a rear position away fromthe above air bearing surface, and a step of forming an air bearingsurface opposed to the magnetic record medium by grinding the abovebasic substance, the magnetic pole portion of the first and secondmagnetic layers and the gap layer placed therebetween.

In a suitable embodiment of the manufacturing method of the thin filmmagnetic head according to the present invention, the above secondmagnetic layer is formed in such a manner that the width of a magneticlayer in a rear region is gradually expanded than the magnetic poleportion.

Moreover, in a suitable embodiment of the manufacturing method of thethin film magnetic head according to the present invention, beforeforming the gap layer where the above first magnetic layer consists atleast of non-magnetic material on the magnetic pole portion, theinsulation layer where the edge on the magnetic pole portion sidebecomes a reference position to the air bearing surface, is formed, andin case of forming the gap layer, the above insulation layer is coveredwith non-magnetic thin film which forms the gap layer.

Moreover, in the manufacturing method of the thin film magnetic headaccording to the present invention, a magnetoresistive readingreproducing element insulated in electrically and shielded inmagnetically is arranged between the above basic, substrate and thefirst magnetic layer to construct a composite thin film magnetic bead.

In case of manufacturing such a composite type thin film magnetic head,the first shield layer for performing a magnetic shielding on the abovebasic substrate, the magnetic resistance material film is formed thereonwhile being embed in a fourth insulation layer, after which the abovefirst magnetic layer also serving as the second shield layer is formed,and in the grinding step for forming the above air bearing surface, theabove first shield layer is ground and the above magnetic resistancematerial film is ground, thereby forming a magnetoresistive reproducingelement which exposes its end surface on the air bearing surface.

BRIEF EXPLANATION OF DRAWINGS

FIGS. 1a, 1b-9a, and 9b are cross-sectional views normal to the airbearing surface and cross-sectional views parallel to the air bearingsurface in the successive manufacturing steps of a conventional standardthin film magnetic head;

FIG. 10 is a cross-sectional view normal to the air bearing surface ofthe conventional completed thin film magnetic head;

FIG. 11 is a parallel cross-sectional view parallel to the air bearingsurface of the magnetic pole section of the conventional completed thinfilm magnetic head;

FIG. 12 is a plan view of the conventional completed thin film magnetichead;

FIGS. 13a, 13b-18a, and 18b are parallel cross-sectional views normal tothe air bearing surface showing the successive manufacturing steps inone embodiment of the manufacturing method of the thin film magnetichead according to the present invention;

FIG. 19 is a plan view showing one embodiment of the shape of the secondmagnetic layer;

FIG. 20 is a plan view showing other embodiments of the shape of thesecond magnetic layer;

FIGS. 21a, 21b-24a, and 24b are cross-sectional views normal to the airbearing surface and cross-sectional views parallel to the air bearingsurface showing the following steps of the same embodiment;

FIG. 25 is a plan view showing the shape of the suitable third magneticlayer to the shape of the second magnetic layer;

FIG. 26 is a cross-sectional view of the thin film magnetic headaccording to the completed present invention;

FIG. 27 is a plan view of the thin film magnetic head according to thecompleted present invention;

FIG. 28 is a diagrammatic plan view showing other embodiment of the thinfilm magnetic head according to the present invention, in which anextended angle of the portion rear the second magnetic layer is made180°; and

FIG. 29 is a graph showing the relation among the extending angle of arear portion of the second magnetic layer, the overwrite characteristic,and the effective truck width.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIGS. 13-25 show the manufacturing procedures of the thin film magnetichead according to the present invention in step order, and FIG. 26, 27show a cross-sectional view and a plane view of the thin film magnetichead of the completed present invention, respectively. Moreover, inthese figures, a is a cross-sectional view normal to the air bearingsurface, and b is a cross-sectional view by which the magnetic polesection is cut in parallel respect to the air bearing surface. This thinfilm magnetic head, moreover, is a composite type thin film magnetichead formed by stacking an induction type thin film reading magnetichead and the MR writing reproduction element.

First of all, as shown in FIGS. 13a and 13b, an insulation layer 22consisting of for example alumina (Al₂ O₃) on basic substrate 21 withthe thickness of about 3-5 μm.

Next, as shown in FIGS. 14a and 14b, in order to form a lower shieldlayer 23, permalloy is selectively formed with the thickness of about 3μm on an alumina insulation layer 22 by the use of the photoresist filmas the mask and the sputtering method.

Next, as shown in FIGS. 15a and 15b, an insulating layer 24' of aluminais formed with the thickness of about 4-6 μm. After smoothing it by forexample CMP, as shown in FIGS. 16a and 16b, alumina is deposited withthe thickness of 100-200 nm as a shield gap layer 24. Next, a magneticresistance layer 25 composing the MR reproduction element is formed withthe thickness of few tens nm. With the desired shape of mask alignmentof high accuracy, a shield gap layer 26 is formed again. Thus, themagnetic resistance layer 25 is embedded in shield gap layer 24 and 26.

Next, the first magnetic layer 27 is selectively formed with thicknessof about 3-4 μm.

Afterwards, in order to eliminate a stepping level, after forming analumina layer on the entire surface with 5-6 μm thickness, the surfaceof the first magnetic layer 27 in CMP is exposed, and the entire surfaceis made smooth, however, this alumina layer does not appear in thedrawing.

Next, as shown in FIGS. 17a and 17b, in order to decide a throat heightTH and apex angle, after forming an insulation layer 28' is formed byphotoresist with the thickness of 2-3 μm, as shown in FIGS. 18a and 18b,a write gap insulation layer 28 consisting of alumina is formed with100-300 nm thickness.

Moreover, this embodiment shows that after the photoresist insulationlayer 28', which is a reference position by which the throat height THand the apex angle are decided, is formed by the edge on the magneticpole portion side, the write gap insulation layer 28 is formed, but theorder of forming these insulating layers may be made opposite. That is,after write gap insulation layer 28 is formed, the photoresistinsulation layer 28' may be formed. However, if after the photoresistinsulation layer 28' is formed, the write gap insulation layer 28 isformed, and the surface of the photoresist layer 28' is covered with thealumina insulation layer 28, there is following advantages. That is, thethroat height TH is defined as a distance between the edge and the airbearing surface on the magnetic pole portion side of the photoresistinsulation layer 28', in an actual manufacturing process, the positionof the edge of the insulation layer 28' is not seen, so that this edgeis formed at the desired position, and the air bearing surface is groundso as to obtain the desired throat height TH by using this edge as areference position.

On the other hand, in case of forming the thin film coil, afterwards, aheat-treating about 250° C. is performed, but the photoresist layer 28'composing the insulation layer is melt by this heating and thus the sizeof the pattern of the insulation layer is changed. Therefore, the aboveedge position of the photoresist insulation layer 28' is also changed,as a result, the size of the throat height TH which is the length of themagnetic pole portion in which this end is formed as a referenceposition, might also shift from the desired design value. Moreover, theMR height MRH defined as height of the magnetic resistance reproductionelement from the air bearing surface is decided as well as the abovedescribed throat height TH depending on the amount of polishing in caseof grinding the air bearing surface, but this grinding is performed byusing the edge of the pole portion side of the photoresist insulatinglayer 28' as a reference position, so that if the edge position of theinsulating layer is changed by heat-treating, MR height MRH is alsochanged, and thus it is not possible to perform the grinding accordingto the design value. In addition, when the photoresist layers 33 and 35constituting the insulating layer for isolating the photoresist layer28' and the thin film coil described later, are melt, it is fear thatthe apex angle θ defined by the inclination angle on the side of theseinsulating layers changes. The apex angle θ also influences on thecharacteristic of the thin film magnetic head, and the characteristicthereof often becomes defective by its change. Therefore, it isimportant to prevent the edge in the photoresist layer 28' constitutingthe insulating layer from changing by heat-treating about 250° C. addedin case of forming the thin film coil. As shown in FIGS. 18a, and 18b,if after forming the photoresist insulating layer 28', an aluminainsulating layer 28 of the write gap is formed, and the photoresistinsulating layer 28' is covered with alumina insulating layer 28, theedge position of the photoresist insulating layer 28' does not change bythe above described heat-treating, so that in addition to the throatheight TH, the photoresist insulation layer 28' can effectively controlthe gap from the desired design value of MR height MRH and the apexangle θ. Next, as shown in FIGS. 18a and 18b, a second magnetic layer 29(pole chip), deciding the width W of the writing track, is selectivelyformed with the thickness of about 1-4 μm. Afterwards, the write gaparound the pole chip is opened selectively, the pole portion is formedfor example by etching the exposed first magnetic layer 27 with ionmilling. Moreover, in the present invention, the pole portion means asshown in FIG. 18a by H, a region, in which the first magnetic layer 27,the write gap 28, and the second magnetic layer 29 (pole chip) betweenthe edge surface of the laminated layers and the edge of the photoresistinsulating layer 28', are connect with the width W. Therefore, in thestage of the product, when the edge surface is ground and the airbearing surface is formed, the pole portion becomes a region from theedge of the photoresist insulating layer 28' to the air bearing surface.

Well, in the present invention, in case of forming the above pole chip,as shown in FIG. 19, it is important to form a second magnetic layer 29with not only pole portion 30, but also over a rear region widely. Thereason thereof is that at the hitherto, in case of forming the secondmagnetic layer while touching the upper pole on the pole chip, thecontact area of the pole chip and the upper pole is small, and thecontact section touches it vertically, so that it is easy to saturatethe magnetic flux in this portion, and thus, the writing characteristicof satisfying enough was not obtained; however, according to the presentinvention, the contact region of the pole chip and the upper pole isextended to not only the magnetic pole portion, but also a rear regiontherefrom, so that the fear of the saturation of such a magnetic fluxcan be effectively canceled, as a result, it comes to be able to obtaina satisfying enough a writing characteristic. Herein, when the contactarea is secured enough, the contact region of a pole chip and an upperpole may be only as a rear region rather than that of the pole portion.

Moreover, in this specification, the rear direction means the directionopposite to the air bearing surface.

Herein, as to the shape of the pole chip in a rear region from the poleportion, a limitation is not present especially. That is, as shown inFIG. 19, if may be a shape postponed straight backward, and as shown inFIG. 20, it may be a shape which widened gradually while going backward.In short, the pole chip only has to come in contact from the poleportion in a rear region with an upper pole by an enough area.

Moreover, the extended length h of the pole chip from pole portion tothe rear side is preferably about 2-5 μm of the ring shaped insulatinglayer 28 which does not exceed its width, particularly, it is preferableto do as the thickness level of a top pole particularly desirable.Moreover, in FIG. 20, when the width angle of the pole chip in a rearregion was assumed to be 90° (One side 45°) from the pole portion, itwas showing the width widening angle is not the one of the best only tothis but 180° or less. There are not any problems. Especially, adesirable range of the angle is 40-180°. In this way, as shown in FIG.20, when the rear end of the pole chip has widened in the shape of fan,not only the saturation of the magnetic flux is not caused as describedabove, but also an accurate pattern edge according to photolithographycan be controlled by enlarging the rear end, so that a more accuratecontrol becomes possible from the throat height's TH. Moreover, in caseof forming the pole chip 29 as described above, if a dummy pattern 29'for connecting a lower pole (the first magnetic layer) and an upper pole(the third magnetic layer) at the same time, an opening of through-holebecomes easy after CMP. As described above, after forming the secondmagnetic layer 29, as shown in FIGS. 21a and 21b, After forming forexample alumina film 31 as the insulation layer is formed with thethickness of about 3 μm, the whole is smoothed by, for example, CMP. Asshown in FIGS. 22a and 22n, then, after forming the thin film coils 32of the first layer consisting of for example copper on this insulationlayer 31, insulative photoresist layer 33 is formed with the maskalignment of high accuracy. Subsequent, the whole is baked by thetemperature of for example about 250° C. to make the surface smooth.Next, as shown in FIG. 23a and 23b, after forming thin film coils 34 ofthe second layer and then after forming photoresist layer 35 with highlyaccurate mask alignment on this thin film coil 34, it bakes at forexample 250° C. to make the surface smooth again. Next, as shown inFIGS. 24a and 24b, the third magnetic layer 36 (upper pole) consistingof for example permalloy is selectively formed with thickness of 3 μm onthe second magnetic layer 29 (pole chip), the photoresist layer 33 and35 according to the desired pattern. In case of forming this thirdmagnetic layer 36, as shown in FIG. 24a, it is suitable for its tipportion to form so as to retreat only distance L from the air bearingsurface. The distance L is almost equal to the throat height TH.Composing in such a way, as described above, if a positional relationbetween the pole chip and the upper pole is shifted greatly to one side,seeing from the air bearing surface, data writing is caused even in theupper pole, a disadvantage of widening the width of the effective trackis caused. However, there is an advantage that such a disadvantage comesmight not generate if making the tip portion of the third magnetic layeris retreated from the air bearing surface. Moreover, hitherto, thoughthe saturation of the magnetic flux is forced since the contact area ofthe pole chip and the upper pole decreases when the tip portion of theupper pole is located from the air bearing surface backward, however, inthe present invention, since the contact area of both is secured enoughin a rear region from the magnetic pole portion, so that the magneticflux might not be saturated even if the tip portion of the upper pole ismade retreated from the air bearing surface. Moreover, in case offorming the third magnetic layer 36, as shown in FIG. 20, it ispreferable to make the shape along the shape of the second magneticlayer 29. In addition, as shown in FIG. 25, when the width angle of thesecond magnetic layer 29 is 30-60° and somewhat small, First, the thirdmagnetic layer 36 is formed with a width widening angle: 30-60° so as toalong the shape of the second magnetic layer, and then is formed withbecoming a desired width angle. Thus, when the width of the thirdmagnetic layer 36 is made wide as the magnetic layer is located awayfrom the air bearing surface, and the third magnetic layer covers thesecond magnetic layer 29, even if a positioning error is caused betweenthe pole chip 29 and upper pole 36, the change of contact area is few asa whole, so that the saturation of the magnetic flux does not generate.Moreover, this third magnetic layer 36 comes in contact with the firstmagnetic layer 27 at a rear position away from the magnetic pole portionthrough the dummy pattern 29', it is thin film coil 32 as for the closedmagnetic path constituted with the first and the second and the thirdmagnetic layer It is structure which passes 34 and comes off.

Next, as shown in FIGS. 26a and 26b, an overcoat layer 37 consisting ofalumina or the like is deposited on the exposed surface of the thirdmagnetic layer 36. Finally, the air bearing surface 38 opposed to themagnetic record medium is formed by grinding the side surface where themagnetic resistance layer 25 and the gap layer 28 are formed. In thiscase, the edge on the magnetic pole portion side of the photoresistinsulation layer 28' is defined as a reference position to the airbearing surface, so that the throat height TH, the MR height MRH, andthe apex angle θ can be decided accurately as a desired design value.The present invention is not limited to the above embodiment and variouschanges and modifications may be performed. In the above describedembodiment, for example, the thin film magnetic head is constructed as acomposite type thin film magnetic head which is formed by stacking aninduction type writing magnetic head and the reading magnetic headcomprising an MR reproduction element, but this can also be constructedas induction type writing magnetic head.

Moreover, in the above embodiment, the width of rear portion of thesecond magnetic layer and the tip portion of the third magnetic layerwhich is overlapped thereto is widened gradually seen from the airbearing surface, but as shown in FIG. 28, the connection portion of themagnetic pole portion of the second magnetic layer 29 and the rearportion may be made a right-angle. In this case, the widening angle ofrear portion of the second magnetic layer 29 may be 180°. Moreover, theshape of portion of the 3rd magnetic layer 36 overlapped to the rearportion of this second magnetic layer 29 is also registered to the shapeof the rear portion with a certain width. FIG. 29 shows the change inthe overwrite characteristic (curve A) obtained when the widening angleα of the rear portion of the second magnetic layer 29 is changed over arange of 0-270° and shows the change in width of the effective trackwidth (curve B). That is, the overwrite characteristic is shown to aleft vertical axis by the dB unit, and the normalized effective trackwidth is plotted ton the right horizontal axis by arbitrary unit. Ingeneral, it is demanded to make the overwrite characteristic to be -30dB or less, and the width of the effective track is allowed to the valueto be originally obtained with extension up to 10% or less. Therefore,it is understood that the widening angle α of a rear part of the secondmagnetic layer 29 is 40-180° from curves A and B. In the presentinvention, as a material for the second magnetic layer, that is, thepole chip, in addition to the above permalloy (Ni:50 wt %, Fe:50 wt %)and nitride iron (FeN), the materials of the high saturation magneticflux density such as Fe--Cr--Zr system amorphous alloys and the Fe--Csystem amorphous alloys are advantageously adopted. Moreover, it is allright in any way to use these materials with two kinds or more.Moreover, as a material for the first and the third magnetic layers, inaddition to the above permalloy (Ni:80 wt %, Fe:20 wt %), well-knownvarious high saturation magnetic flux density materials can be suitablyused.

In addition, as a material for the write gap layer, Oxide such as Al₂O₃, SiO₂ or the like, Nitride such as AIN, BN, SiN or the like,furthermore, electrically conductive and non magnetic substance such asAu, Cu, NiP or the like are used effectively.

Moreover, in the above example shown in the figure, it is explainedchiefly described the case that the insulating layer, in which edge onthe pole portion side became a reference position to the air bearingsurface, is formed with the photoresist layer, but this insulating layermay be formed with the alumina layer, the silicon oxidation layer, andthe silicon nitride layer, or the like.

According to the present invention, the second magnetic layer (polechip) and the third magnetic layer (upper pole) have been touched at notonly the pole portion but also it in a wide rear region therefrom, sothat it is possible to reach the writing pole region effectively withoutsaturating magnetism generated in the coil on the way, and thus asatisfactory writing characteristic can be obtained.

Moreover, according to the present invention, the insulating layer inwhich the edge on the pole portion side becomes a reference position tothe air bearing surface is provided on the first magnetic layer, and ifthis insulating layer is covered with the write gap alumina layer, theinsulating layer does not melt by heat-treating added at the time offorming the thin film coil, so that the throat height TH and the MRheight MRH and furthermore, the apex angle θ can be formed according toa desired design value.

According to the present invention, the desired relation is alwaysobtained between the MR height MRH and the throat height TH, so that thebalance of the record head and the reproduction head can be kept in thebest condition, and as a result, a composite type thin film magnetichead can be obtained with high performance.

In addition, according to the present invention, the tip portion of thethird magnetic layer is made retreated from the air bearing surface. Thecontact portion of the third magnetic layer and the second magneticlayer is prevented from being exposed to the air bearing surface, sothat even if as seen from the air bearing surface, mis-registration iscaused in the position of a pole chip and an upper pole, the writing isperformed by the upper pole, and thus the width of the effective trackcan be effectively prevented from being widened.

Moreover, further according to the invention, the contact area of anupper pole and the pole chip can be increased, by widening the rear endof the second magnetic layer in the shape of fan, so that magnetic fluxcan be effectively prevented from being saturated in this portion.

Additionally, when the shape of the third magnetic layer is made wide,and the second magnetic layer is covered, even if the error is caused inthe positional registration of both magnetic layers, the change of thecontact area is little as a whole, so that magnetic flux can beprevented from being saturated.

What is claimed is:
 1. A thin film magnetic head comprising:a first magnetic layer having a pole portion; a second magnetic layer having a pole portion with a width that defines a width of a record track; an air bearing surface formed in part by an end face of the pole portion of the first magnetic layer and an end face of the pole portion of the second magnetic layer; a third magnetic layer contacting the second magnetic layer on a side opposite the first magnetic layer, the third magnetic layer being magnetically coupled to the first magnetic layer at a rear position separated from the air bearing surface; a gap layer of a non-magnetic material inserted between the pole portion of the first magnetic layer and the pole portion of the second magnetic layer; a thin film coil having a portion supported between the first magnetic layer and the second and third magnetic layers, the thin film coil being isolated by an insulating layer, the insulating layer forming a coplanar surface with the second magnetic layer, the thin film coil being formed on the coplanar surface of the insulating layer; and a base substrate supporting the first, second and third magnetic layers, the gap layer, the insulating layer and the thin film coil; wherein the second magnetic layer extends to a region beyond the pole portion of the first magnetic layer and against a face of the insulating layer, the third magnetic layer touching the second magnetic layer at the extended region on the side opposite the first magnetic layer.
 2. The thin film magnetic head as claimed in claim 1, wherein the width of the second magnetic layer is widened at the region beyond the pole portion.
 3. The thin film magnetic head as claimed in claim 2, wherein the width of the second magnetic layer is widened to an angle of 40-180° at the region beyond the pole portion.
 4. The thin film magnetic head as claimed in claim 1, wherein a length h of the region of the second magnetic layer beyond the pole portion is substantially 2-5 μm.
 5. The thin film magnetic head as claimed in claim 1, wherein the second magnetic layer comprises a substance having a high saturation flux density.
 6. The thin film magnetic head as claimed in claim 1, wherein a tip portion of the third magnetic layer is spaced from the air bearing surface so as not to expose the touched portion of the third magnetic layer and the second magnetic layer on the air bearing surface.
 7. The thin film magnetic head as claimed in claim 6, wherein a width of the third magnetic layer is greater than a width of the second magnetic layer at the region beyond the pole portion.
 8. The thin film magnetic head as claimed in claim 6, wherein the tip portion is spaced a distance substantially equal to a throat height.
 9. The thin film magnetic head as claimed in claim 1, further comprising:an insulation layer provided on the first magnetic layer, the insulation layer having an end edge which forms a reference position for the air bearing surface, the gap layer of the non-magnetic material covering the insulation layer, at least a portion of the second magnetic layer being arranged along a surface of the gap layer opposite the insulation layer.
 10. The thin film magnetic head as claimed in claim 1, wherein the pole portion of the first magnetic layer is a trim structure.
 11. The thin film magnetic head as claimed in claim 1, wherein an electrically insulated and magnetically shielded magnetoresistive reading reproducing element is arranged so as to expose its end face on the air bearing surface between the base substrate and the first magnetic layer so as to form a composite thin film magnetic head. 